Apparatus for utilizing cumulative ionization



July 8, 1 E. G. LINDER APPARATUS FOR UTILIZING CUMULATIVE IONIZATION Filed April '29, 1949 fer/z/ 50052: W

INVENTOR I ATTORNEY patented July 8,1952

UNETED STATES APPARATUS FOR UTILIZING CUMULATIVE IONIZATION Ernest G. Linder, Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application April 29, 1949, Serial No. 90,332

8 Claims.

This invention relates generally to high-frequency radio devices and more particularly to such devices in which ionization of the medium within a tube of the device is involved in the operation of the device.

In my copending U. S. patent applications, Serial Numbers i9,736 and 66,113, filed on September 17, 1948, and December 18, 1948, respectively, now respectively Patents Nos. 2,548,225 and 2,540,537, therewere disclosed and claimed certain radio tubes and associated circuits that depended for their operation on the cumulative ionization of the medium within the tubes, which ionization was produced by the trapping of the electrons within the tube envelopes.

In the present invention, a high frequency electric field is combined with a magnetic field of critical intensity value, proportional to the frequency of the electric field, whereby a resonance condition is produced between the orbits of the electrons and the applied radio frequency electric field. Under these conditions the electrons will absorb energy from the high frequency field and this energy is available for ionization. With this ionization, the ion density is increased rapidly and a short build-up time is had.

Under these critical operating conditions, it is notnecessary either to coat the cathode or heat the cathode as the increased ionization starting from residual free electrons in the med ium becomes a new source of electrons for the cumulative ionization.

My discovery is applicable generally to high frequency devices that depend for their operation on cumulative ionization. For example: the efficiency of operation of a transmit-receive (TR) tube in a radar system, used to isolate the receiver from the transmitter during transmission periods, depends upon increases in ion densities and the rapidity of ionization and deionization of the medium within the tube. I have increased the rapidity of these functions and increased the ion density by applying a magnetic field generally at right angles to the plane of the paths of the electrons in the medium within the tube and adjusting the strength of the magnetic field to such a value that the frequency of electron motion is equal to the operating frequency of the system. With such an arrangement it is practical to operate the tube at lower pressures.

It has been discovered that when this resonance relation of the frequency of electron motion to the operating frequency is applied to a device or system, a much more positive or augmented ionization occurs and an improvement in operating. efiiciency is had.

21rfm I e where ,f is the operating frequency of the device in cycles per second and H, m and e are in MKS units, as in Equation 1.

In the remainder of this specification and the appended claims, this equation will be identified as Equation 2."

This discovery is applicable with equally beneficial results in operation, to other high-frequency devices, such as demodulators, rectifiers and magnetrons, as will be fully described hereinafter.

The principal object of the invention is to provide an improved method of and means for increasing the efficiency of operation of high frequency radio tube devices operating with intermittant ionization, by applying thereto magnetic fields of critical values.

Another object of the invention is to provide an improved method of and means for increasing the efficiency of operation of said high frequency radio tube device by applying thereto magnetic fields of a strength proportional to the frequency of electron rotation frequency of the device.

Another object of the invention is to provide an improved methods of and means for increasing the emciency of operation of said high frequency radio tube devices by applying thereto a magnetic field of a strength represented by Equation 2 hereof.

A further object is to provide improved methods of and means for operating cold cathode tubes in a manner wherein the charged particles due to ionization traverse orbits resonant to the operating frequency.

Other objects of the invention Will be apparent from the various embodiments and features of the invention as will be described in detail hereinafter and by reference to the accompanying drawings in which:

Figure 1 is a line sketch of a TR. tube coupled. to a wave guide and upon which tube is impressed a magnetic field;

Figure 2 is a line sketch of a demodulator tube and associated circuits, upon which tube is impressed a magnetic field;

Figure 3 is a line sketch of a coaxial conductor on an evacuated portion of which is impressed a magnetic field, the coaxial conductor being connected to associated circuits to form a high frequency rectifier;

Figure 4 is a line sketch in perspective of a novel ionizable split anode magnetron upon the medium of which is impressed a magnetic field;

and I Figure 5 is a line sketch in cross section of a novel ionizable multicavity magnetron upon which is impressed a magnetic field.

Like reference characters refer to like elements throughout the drawings.

With reference to Figure 1, numeral 1 represents the cavity resonator of a TR tube or box inwhich are positioned the electrodes 2 and 3. This tube I is connected physically to wave guide 4 and is coupled thereto through window 5. Around the two electrodes 2 and 3 are positioned the magnet coil 6. The strength of the magnetic field is adjusted in accordance with Equation 2 hereof.

The magnetic field is indicated by the arrow H as being generally at right angles to the paths of'electrons from electrode 2 to electrode 3. Due

to the general shape of electrode 3 in relation to that of electrode 2, the magnetic field could be impressed upon the medium at right angles to that shown by the arrow H.

In operation: When a voltage difference first appears between electrodes 2 and 3 due to the voltage rise at the beginning of a transmitter pulse, a few free electrons start to fiow therebetween. V

In all TR tubes, the density of the electrons flowing between the electrodes must rise to a considerable value before the medium becomes sufliciently conductive. In accordance with the in stant invention, by applying a magnetic field of the critical value to the medium as hereinbefore defined, the free electrons are trapped within the medium, their paths become much longer and ionization of the medium occurs at-a greater rate.

It has been found in operation'that when a critical magnetic field is impressed on the tube, the pressure within the tube can be lower than that usually required for these tubes. The mean free path for molecular collision is longer for the lower pressures and provides faster deionization. Gas pressures of 10 and 10 mm. of Hg have been found to give excellent results.

My discovery has been applied to a section of a coaxial line conductor to provide, with outside circuits, a more efficient demodulator, which provides better high frequency response and eliminates the necessity for a hot cathode. In Figure 2, a section of the coaxial conductor 1 is blocked off by glass beads 8 and the outer section of the conductor is expanded to form the anode-envelope 9. Cold cathode ID is positioned axially the envelope 9 and is connected to'the axis conductor II. A magnetic field is impressed upon the medium within envelope 9 by theelectromagnetic coil 6.

Connected to envelope 9 and cathode I0 is an adjustable section shown generally at l2, Which is tuned for optimum operation by moving the piston I3 by handle I4.

4 In operation: The outer conductor [5 of the resonant section I2 is maintained positive by the electric source It, which is connected also through the primary ll of transformer 13 to the axial conductor ll. Capacitor l9 parallels electric source IE to by-pass the demodulated frequencies. The

- output energy is withdrawn from the circuit from I My discovery has been applied to a high-frequency rectifier, as shown in Figure 3, which operates under the same general principles including a magnetic field, as the demodulator shown in Figure 2, except that the arrangement operates over other portions of the characteristic curves of the tube, as is well known in the art. However, the efficiency of the arrangements, as in the case of the demodulator is increased when a magnetic field of critical value is applied to the medium between glass beads 8 in which is located the cathode 53 which includes contiguous end plates Illa. The anode 9 is a section of-the outer conductor [5, separated physically from the conductor 1 by capacitor connection 20. "The resonant cavity 52 is tuned by sliding piston l3 which is moved by handle l4. Outer'anode conductor i5 is maintained at a positive potential from source l6, which is by-passed by capacitor it. The output of the rectifier 'is through a filter comprising inductor 2i and capacitor 22.

One side of capacitor 22 is connected to ground the electric source l5 and capacitor l9.

In Figures 4 and 5 are shown magnetrons of the split anode type and the resonant multicavity type, respectively. These differ from the conventional types in that, among other things,- they have gaseous media of a predetermined very low pressure range. In applying my discovery to magnetrons, the magnetic field is made to serve two purposes. First, it is used to provide the operating field of the tube and secondly, it is used to provide the trapping magnetic field of the critical value whereby ionization of the gaseous medium of the tube is accomplished.

In Figure 4, the magnetic field is applied by magnet poles 25 upon the medium of the tube between cathode l3 and split anode section 26. The magnetic field may also be produced and adjusted to the critical value for the frequencies involved, by substituting an electromagnetic coil and a source of variable electric power.

In Figure 5, there is shown the application of my discovery to a multicavity magnetron. The magnetic field is applied by permanent magnet poles 25 to the magnetron through the nonmagnetic material forming the envelope and body 21 of the magnetron. Cathode H) is mounted in the axis of the central resonance chamber which is in communication with cavities 28 through slits in the main body. Slits 29 connect the central chamber with other cavities, not shown. As hereinbefore pointed out the cathode ill need not be coated or heated. The pole pieces 25 may be. shaped, such as is shown at 30, to apply a nonmagnetron.

Therelation between the variables as defined in Equation ,1, does not apply strictly to the multicavity type of magnetron as the interaction between cavities in a multicavity magnetron is well known to be difierent from the interaction between circuits connected toa multisector or split anode type or" magnetron. vHowever, there does exist for the multicavity mag-netrons a relation between the operating frequency, the anode voltage and the impressed magnetic field as expressed by the equation:

where V is the anode voltage, Tp is the anode radius, Ta is the cathode radius, a is the ratio of the angular frequency of the electronto the angular veloci y or? the electron, he is the operating wave length and Bi is the magnetic field (see Vacuum Tubes by Spangenberg, equation 13.9812, page 662).

In the claims appended hereto, this equation will be identified as Equation 3.

There is thus provided methods of and means for operating high-frequency radio tubes at greater eiiiciencies and using gaseous mediums at relatively low pressures, by applying critical values of magnetic fields to the medium of the tubes, defined by the Equations 2 and 3 hereof, to effect prompt trapping of the electrons in resonant orbits within the medium of the tube and thereby cause cumulative ionization.

I claim as my invention:

1. A transmit-receive switch for a high-frequency wave guide system comprising: means forming a cavity resonator tuned by dimensions to said frequency, means coupling said cavity resonator to said guide, two electrodes mounted respectively on opposite electric-field sides of said cavity resonator and in spaced relation to each other, and means adjacent said electrodes for applying a magnetic field upon the medium within the cavity resonator.

2. A transmit-receive switch for a high-frequency wave guide system comprising: means forming a cavity resonator tuned by dimensions to said frequency, means coupling said cavity resonator to said guide, two electrodes mounted respectively on opposite electric-field sides of said cavity resonator and in spaced relation to each other, and means adjacent said electrodes for applying a magnetic field upon the medium within the cavity resonator, and generally at right angles to the electro-static field between said electrodes.

3. A transmit-receive switch for a high-frequency wave guide system comprising: means forming a cavity resonator tuned by dimensions to said frequency, means coupling said cavity resonator to said guide, two electrodes mounted respectively on opposite electric-field sides of said cavity resonator and in spaced relation to each other, means adjacent said electrodes for applying a magnetic field upon the medium within the cavity resonator, and generally at right angles to the electrostatic field between said electrodes, and means connected to said magnetic 6 4 field means for adjusting the intensity H of said field in accordance with the equation.

where e is the charge and mis the mass of the electron in MKS units, and f is the frequency in cycles per second of electron orbital motion, whereby the electrons are trapped between said electrodes an cumulative ionization of. said medium occurs.

4. Ademodulator device includinga highfrequency coaxial conductor system, means pressure isolating a section of said system, the pressure within the said isolated section being less than atmospheric pressure, a cold emission cathode within said section connected to the axial conductor of said system, an anode coupled to the outer conductor of said system, a tunable resonant coaxial conductor section coaxial with and connected to said pressure isolated section, an

output circuit connected to said tunable section, and means adjacent said section for applying a magnetic field upon the medium within the said pressure isolated section. v

5. A demodulator device including a high-frequency coaxial conductor system, means pressure isolating a section of said system, the pressure within the said isolated section being less than atmospheric pressure, a cold emission cathode within said section connected to the axial conductor of said system, an anode coupled to the outer conductor of said system, a tunable resonant coaxial conductor section coaxial with and connected to said pressure isolated section, an output circuit connected to said tunable section, means adjacent said section for applying a magnetic field upon the medium within the said pressure isolated section, and means for adjusting the intensity H of said magnetic field in accordance with the equation where e is the charge and m is the mass of the electron in MKS units, and j is the frequency in cycles per second of electron orbital motion, whereby the electrons are trapped in resonant orbits between said electrodes and cumulative ionization of said medium occurs.

6. A rectifier device for a high-frequency coaxial conductor system comprising: means pressure isolating a section of said system, the pressure within the said isolated section being less than atmospheric pressure, a cold emission cathode within aid section connected to the axial conductor of said system, an anode capacltatively coupled to the outer conductor of said system, a

tunable resonant coaxial conductor section co-- axial with and connected to said isolated section, an output circuit connected to said tunable section, and means adjacent said section for applying a magnetic field upon the medium within the said pressure isolated section.

7. A rectifier device for a high-frequency coaxial conductor system comprising: means pressure isolating a section of said wave guide, the pressure within the said isolated section being less than atmospheric pressure, a cold emission cathode within said section connected to the axial conductor of said system, an anode capacitatively coupled to the outer conductor of said system, a tunable resonant coaxial conductor section coaxial with and connected to said isolated section, an output circuit connected to said tunable section, inea'ris adjacent said section for applying "'a magnetic fi'el'd upon the medium within the said pressure isolated section, and means for adjusting 'the intensity H of said magnetic field in accordance with the equation electrodes and cumulative ionization of said medium occurs.

'8. A high f-requen'cy radio"circuit including "a tube having a pair of cold el'ectrodesand which depends for its operation upon charged particles produced by ionization of the medium hemmed Within the "tube 'C'dli'i'idrisiffg: "means connected to said tube for impressing high frequency wave energy 'upon said medium, means including s'ai'd electrode f dr geniafing 'chargedbaiticle 001d emission *Wi-thin said medium, means connected to said electrodes for accelerating said emission. means adjacent said electrodes for impressing "a magnetic field on'said medium, means connected to-said 'm'agnetic field means for adjusting the in 8 tensity ofsai'd field to *caus' said emission to for-- lowbrbitsiresonant to the frequency of said higm i'r-"eque' y enrgy Whereby'sa'id emitted charged partic embed-eta :p'o'rtion of said high-frequency wave energy 'a'nd' whereby said absorbed enrgy provides for cumulative ionization of said-medium whereby the ion densit y 'the'r'ein is rapidly in-- creased When-said nigh -frequency energy is-ea inane 

